Solid Waste: Collection, Treatment and Disposal | Civil Engineering Optional Notes for UPSC PDF Download

Recycling in Solid-Waste Management

Overview: Recycling involves separating, recovering, and reusing components of solid waste that still have economic value. It helps lessen the burden on landfills and conserves natural resources by substituting raw materials.

Separation:

• Source Separation: Also known as curbside separation, this method involves individuals sorting their waste into categories like newspapers, bottles, cans, and garbage. Municipal collection of source-separated refuse can be more expensive than regular refuse collection.
• Centralized Separation: Recyclable materials are separated at centralized mechanical processing plants. This method often results in lower-quality recyclables due to contamination with moist garbage and broken glass. The preferred practice involves citizens separating refuse into categories such as newspapers, wastepaper, commingled metals, glass, plastics, and nonrecyclables.

Processing at Material Recycling Facilities (MRFs):

• Commingled Recyclables: At an MRF, commingled recyclables are loaded onto a conveyor. Steel cans are removed by an electromagnetic separator. Broken glass is removed by a vibrating screen, while an air classifier separates aluminum and plastic containers from heavier glass containers. Manual sorting further separates glass by color, and aluminum cans are separated from plastics by an eddy-current separator.

Reuse of Recycled Materials

• Glass: Crushed and used in asphalt pavement or sold to manufacturers as cullet for glassmaking.
• Steel Cans: Baled and shipped to steel mills as scrap.
• Aluminum: Baled or compacted for reuse by smelters; highly valued for recycling.
• Plastics: Mixed thermoplastics can be used to make lower-quality products like plastic lumber.
• Paper: Old newspapers are sorted and shipped to paper mills for reuse. Mixed paper is separated from corrugated paper for sale to tissue mills.
• Rubber: Reclaimed rubber can be used in asphalt pavements, artificial turf, or as outdoor mulch. Discarded tires may be repurposed for recreational structures in playgrounds.

• Market Demand: The biggest challenge in recycling is finding applications and suitable markets for recycled materials. Recycling alone cannot solve the growing problem of solid-waste management and disposal. There will always be some residue requiring final disposal.

Importance and Impact:

• Conservation of Resources: Recycling reduces the need for raw materials from natural resources like petroleum, natural gas, coal, mineral ores, and trees.
• Environmental Benefits: Recycling helps reduce pollution of air, water, and land resulting from waste disposal.
• Economic Factors: The choice to recycle depends on economic conditions. Recycling becomes attractive when the cost of reprocessing waste is lower than the cost of treating and disposing of materials or processing new raw materials.

Recycling remains a crucial part of solid-waste management, offering a sustainable way to manage waste, conserve resources, and reduce environmental impact.